1. Field of the Invention
This invention relates in general to a nibbling machine construction and in particular to a new and useful device for controlling the feed of the workpiece in respect to a nibbling punch so that the most advantageous feed thereof may be effected during the lift off of the punch from the workpiece.
2. Description of the Prior Art
The present invention relates to a feed control for a nibbling machine including, in particular, longitudinal and cross feed mechanisms, in which the feed drive is released only during the time that the punch is disengaged from the workpiece. As is well known, the workpiece can be fed only within the period of time during which the punch is off the workpiece. A suitable arrangement ensures that the feed motors can be put in operation only within this time of feed release. Assuming a quite definite stroke of the punch, such an arrangement means that the time of feed release becomes the shorter the thicker the material to be nibbled is. On the other hand, the thickness of the material is also one of the determining criteria for the feed step. If now with nibbling machines of the prior art, the magnitude of the feed step and of the feed velocity is predetermined, as a rule, the following happens: with a feed velocity which is too small, the provided feed step is not accomplished, since upon expiration of the time of feed release, the feed motion is stopped. If, on the other hand, the adjusted feed velocity is too large, the feed stops prior to the expiration of the time of feed release, i.e., the velocity and acceleration of the feed motion of the workpiece are unnecessarily high and, consequently, the machine is loaded to an unnecessary degree.